Banana peel bio-waste hydrogels modified with carboxymethyl groups for the removal of cationic dyes

Abstract

Dye removal from wastewater is a challenge to be addressed, since these cause environmental problems, affecting the development of life in different systems. Nonetheless, most of the dyes are strongly resistant to the usual treatment of conventional wastewater plants, and, therefore, cost-effective and efficient methodologies for their removal are needed. Against this background, this research proposes the formation of a hydrogel from the functionalization of the lignocellulosic material from the banana peel with carboxymethyl groups, and the subsequent cross-linking with citric acid. As a reference, the same derivatives were obtained from bananapeel cellulose, and then all samples were characterized by ATR-FTIR, confirming the esterification reaction. Subsequently, the dye removal efficiency was evaluated using Safranin and Methylene blue. The target material showed a retained capacity of 92.5 ± 1.4 % for Safranin and 88.9 ± 0.1 % for Methylene blue, results higher than those obtained with cellulose derivatives (< 83 %). Therefore, this research demonstrates the synthesis of hydrogels from banana peel without prior cellulose extraction, and the potential application of it in cationic dye removal from polluted waters.